Efficacy and safety of radioiodine in the treatment of disseminated differentiated thyroid cancer (DTC) in children

Abstract

10065 Background: Distant metastases, mainly to lung are diagnosed in about 20% of children with DTC. At present radioiodine is the treatment of choice in that case. However, it can results in massive lung fibrosis as was showed in historical groups of patients.The aim of this retrospective study was to evaluate results of radioiodine therapy in children and its long-term safety. Methods: From 235 children (median age 13.9) diagnosed either with papillary (82%) or follicular cancer (18%), 42 (17.9%) had lung, and 2 (9%) bone metastases (median time of observation 105 months). All were treated with radioiodine (accumulated activities 100 to 950 mCi). Treatment results were evaluated by means of scintigraphic, radiological, and biochemical examinations. 28 (67%) of the children were lately re-evaluated with high resolution CT, ultrasound, biochemistry, and spirometry. Results: In most children, 29/44 (66%), distant metastases were diagnosed in radioiodine scan while radiological examinations were normal. Complete scintigraphic and radiological remission was achieved in 38 (86%) children. In all children there was a decrease in thyroglobulin serum concentration after radioiodine therapy. However, it normalized at the last radioiodine treatment only in 13 (29%) cases. During follow-up Tg continued to decrease and at the last stimulated Tg evaluation it was < 10 ng/ml in 28 (64%) patients. In 5/28 (18%) of the children with lung metastases some small foci of focal lung fibrosis were diagnosed with CT. However, comparable percentage of focal fibrosis was observed in DTC children without lung metastases. Also the preliminary results didn't show an increased rate of abnormal spirometry results. Conclusions: Complete remission of distant metastases can be achieved in about 85% of children with DTC treated with radioiodine. This therapy is safe and does not cause any increased risk of lung fibrosis even in children treated with repeated courses of radioiodine. No significant financial relationships to disclose.